<html>

<head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">

    <style>
        body {margin: 0;}
        
        ul.topnav {
            list-style-type: none;
            margin: 0;
            padding: 0;
            overflow: hidden;
            background-color: #333;
        }
        
        ul.topnav li {float: left;}
        
        ul.topnav li a {
            display: block;
            color: white;
            text-align: center;
            padding: 14px 16px;
            text-decoration: none;
        }
        
        ul.topnav li a:hover:not(.active) {background-color: #111;}
        
        ul.topnav li a.active {background-color: #4CAF50;}
        
        ul.topnav li.right {float: right;}
        
        @media screen and (max-width: 600px){
            ul.topnav li.right, 
            ul.topnav li {float: none;}
        }

 li>a:hover:not(a.active),
 .dropbtn:hover {
     background-color: #555;
 }

 .dropdown-content {
     display: none;
     position: absolute;
     /* 默认相对于<html>进行绝对定位 */
     background-color: #f9f9f9;
     min-width: 100px;
     box-shadow: 0 8px 16px 0 rgba(0, 0, 0, .2);
 }

 .dropdown-content a {
     color: black;
     display: block;
     /* 因为<a>标签不是块元素，min-width:100px不会生效 */
 }

 .dropdown-content a:hover {
     background-color: #f1f1f1;
     color: deepskyblue;
 }

 .dropdown:hover .dropdown-content {
     display: block;
 }


    </style>
</head>

<body>
    <ul class="topnav">
        <li><a href="waiwang.html" target="kuangjia"  class="active">主页</a></li>
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        <li>
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    </ul>

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</div>

</body>

</html>
